Seals are known which employ a barrier fluid in combination with stator and rotor seal rings to prevent leakage of product through the annular space around a rotary shaft extending through a pump housing wall or some other object. The barrier fluid typically functions to lubricate and cool the point of interface between the sealing faces and to prevent product from entering the sealing interface. However, the barrier fluid does not always prevent contact between the seal rings, with the less efficient, less stable seal assemblies permitting frictional wear, especially at lower rotations per minute, which reduces the useful life of the seal. In addition, when the barrier fluid is a gas which is distinct from the product being sealed and is injected into the seal, reducing the amount of barrier fluid used and reducing the amount which contaminates product being sealed have proven to be elusive goals.
A need therefore exists for a seal assembly which increases the stability of the sealing rings by reducing the speed at which efficient liftoff occurs at the interface of the sealing rings. A need also exists for a seal assembly which maximizes the efficiency of the barrier fluid in the seal assembly, reduces the amount of barrier fluid contamination, and minimizes the overall amount of barrier fluid required to operate the seal assembly.